CVE-2019-5477: Canonical Ubuntu Linux

Critical severity, CVSS 9.8. EPSS: 5.9% chance of exploitation in the next 30 days.

A command injection vulnerability in Nokogiri v1.10.3 and earlier allows commands to be executed in a subprocess via Ruby's `Kernel.open` method. Processes are vulnerable only if the undocumented method `Nokogiri::CSS::Tokenizer#load_file` is being called with unsafe user input as the filename. This vulnerability appears in code generated by the Rexical gem versions v1.0.6 and earlier. Rexical is used by Nokogiri to generate lexical scanner code for parsing CSS queries. The underlying vulnerability was addressed in Rexical v1.0.7 and Nokogiri upgraded to this version of Rexical in Nokogiri v1.10.4.

Affected products

• Canonical Ubuntu Linux: version 16.04 only; version 18.04 only; version 19.04 only; version 19.10 only
• Debian Debian Linux: version 8.0 only; version 10.0 only
• Nokogiri Nokogiri: up to and including 1.10.3

Published 2019-08-16. Last modified 2026-06-17.